Stone circles in the British Isles and Brittany in the context of "Long Meg and Her Daughters"

A stone circle is a ring of megalithic standing stones. Most are found in Northwestern Europe – especially Stone circles in the British Isles and Brittany – and typically date from the Late Neolithic and Early Bronze Age, with most being built between 3300 and 2500 BC. The best known examples include those at the henge monument at Avebury, the Rollright Stones, Castlerigg, and elements within the ring of standing stones at Stonehenge. Scattered examples exist from other parts of Europe. Later, during the Iron Age, stone circles were built in southern Scandinavia.

The archetypical stone circle is an uncluttered enclosure, large enough to congregate inside, and composed of megalithic stones. Often similar structures are named 'stone circle', but these names are either historic, or incorrect. Examples of commonly misinterpreted stone circles are ring cairns, burial mounds, and kerb cairns. Although it is often assumed there are thousands of stone circles across the British Isles and Europe, such enclosures are actually very rare, and constitute a regional form of henge. Examples of true stone circles include Long Meg and Her Daughters in Cumbria, henges with inner stones such as Avebury in Wiltshire, and The Merry Maidens in Cornwall.

William Stukeley FRS FSA (7 November 1687 – 3 March 1765) was an English antiquarian, physician and Anglican clergyman. A significant influence on the later development of archaeology, he pioneered the scholarly investigation of the prehistoric monuments of Stonehenge and Avebury in Wiltshire. He published over twenty books on archaeology and other subjects during his lifetime. Born in Holbeach, Lincolnshire, as the son of a lawyer, Stukeley worked in his father's law business before attending Saint Benet's College, Cambridge (now Corpus Christi College). In 1709, he began studying medicine at St Thomas' Hospital, Southwark, before working as a general practitioner in Boston, Lincolnshire.

From 1710 until 1725, he embarked on annual tours of the countryside, seeking out archaeological monuments and other features that interested him; he wrote up and published several accounts of his travels. In 1717, he returned to London and established himself within the city's antiquarian circles. In 1718, he was elected a Fellow of the Royal Society and became the first secretary of the Society of Antiquaries of London. In 1721, he became a Freemason and, in 1722, co-founded the Society of Roman Knights, an organisation devoted to the study of Roman Britain. In the early 1720s, Stukeley developed a particular interest in Stonehenge and Avebury, two prehistoric stone circles in Wiltshire. He visited them repeatedly, undertaking fieldwork to determine their dimensions.

Swinside, which is also known as Sunkenkirk and Swineshead, is a stone circle lying beside Swinside Fell, part of Black Combe in southern Cumbria, North West England. One of around 1,300 recorded stone circles in the British Isles and Brittany, it was constructed as a part of a megalithic tradition that lasted from 3300 to 900 BC, during what archaeologists categorise as the Late Neolithic and Early Bronze Ages.

In this period, the Lake District – a mountainous area in which Swinside is located – saw particularly high levels of stone circle construction, with other notable examples including the Castlerigg stone circle and Long Meg and Her Daughters. The original purposes of these circles is still debated, although most archaeologists concur that they were built for ritual or ceremonial reasons. Constructed from local slate, the ring has a diameter of about 93 ft 8ins (26.8m), and currently contains 55 stones, although when originally constructed there probably would have been around 60. An entrance-exit was included on the monument's south-eastern side, which was defined by the inclusion of two outer portal stones.

Castlerigg Stone Circle (alternatively Keswick Carles, or Carles) is situated on a prominent hill to the east of Keswick, in the Lake District National Park, North West England. It is one of around 1,300 stone circles in the British Isles and Brittany, constructed as a part of a megalithic tradition that lasted from approximately 3200 BC to 2500 BC, during the Late Neolithic and Early Bronze Ages.

Various archaeologists have mentioned the beauty and romance of Castlerigg and its surrounding landscape. In his study of the stone circles of Cumbria, archaeologist John Waterhouse commented that the site was "one of the most visually impressive prehistoric monuments in Britain."